Fuel injectors have become common devices on internal combustion engines to control the timing and metering of fuel into the cylinders of the engine. Many fuel injectors are mechanically driven from the camshaft of the engine via a plunger, a cam, a cam follower and a rocker arm mechanism. Since the camshaft rotates in a fixed angular relationship with the crankshaft, the timing of the fuel injection was not adjustable with respect to other engine operating conditions. This presented a problem in that fuel was always injected into the combustion chamber at the same crankshaft position, irregardless of the engine load, speed and other conditions. Such injectors also require complex mechanisms to adjust the metered fuel quantity with respect to these same conditions. Solutions to this problem were presented in U.S. Pat. Nos. 4,235,374 and 4,281,792. in these patents, the fuel injector utilizes a single slide valve which controls the timing and the metering functions of the injector. The movement of the valve is electronically controlled by a solenoid so that rapid movement is possible but a sealing problem is still present. The sealing problem is critical because leakage tends to occur during the downward stroke of the plunger wherein very high injection pressures are created. In addition to the high pressure, the control valve must be able to reciprocate very rapidly thereby compounding the sealing problem.
Now a fuel injector has been invented which utilizes a cylindrical sleeve valve to control the leakage problem when high pressures are created within the timing or metering chambers of the injector.